It gets under your skin and goes to your head. And we're not just talking about the stress. (But it's not all bad news.)

By Jena Pincott

Photo: Thinkstock

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It May Make Biological Clocks Tick a Little Faster

City birds have faster reproductive clocks than country birds, found a recent study at the Max Planck Institutes. And the culprit is something that may affect us all: light pollution. Light that was just one-thirtieth the intensity of a streetlamp made songbirds breed earlier and grow bigger gonads. Even a tiny amount of light can suppress sleep-time levels of melatonin—a well-known antioxidant, explains lead researcher Davide Dominoni. "Reduce melatonin levels in our bodies, and free-radicals likely increase—which age us faster." There's also a possibility that nighttime light affects the "baby clock" because melatonin keeps sex hormones in check, regulates the ovaries and prevents eggs from maturing too quickly. Science has already proven that room lights and LED screens reduce melatonin and throw our bodies off-sync—potentially leading to cancer, obesity and infertility, among other health problems. But exactly how "aging" is the gentle urban glow that seeps through your blinds? Research is ongoing; in the meantime, sleep shades are looking sexier.